arch/x86/kernel/head_64.S - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
  *
  *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
  *  Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
  *  Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
  *  Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
  *  Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
  */


 #include <linux/linkage.h>
 #include <linux/threads.h>
 #include <linux/init.h>
 #include <linux/pgtable.h>
 #include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/msr.h>
 #include <asm/cache.h>
 #include <asm/processor-flags.h>
 #include <asm/percpu.h>
 #include <asm/nops.h>
 #include "../entry/calling.h"
 #include <asm/export.h>
 #include <asm/nospec-branch.h>
 #include <asm/fixmap.h>

 /*
  * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
  * because we need identity-mapped pages.
  */
 #define l4_index(x)	(((x) >> 39) & 511)
 #define pud_index(x)	(((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

 L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
 L4_START_KERNEL = l4_index(__START_KERNEL_map)

 L3_START_KERNEL = pud_index(__START_KERNEL_map)

 	.text
 	__HEAD
 	.code64
 SYM_CODE_START_NOALIGN(startup_64)
 	UNWIND_HINT_EMPTY
 	/*
 	 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
 	 * and someone has loaded an identity mapped page table
 	 * for us.  These identity mapped page tables map all of the
 	 * kernel pages and possibly all of memory.
 	 *
 	 * %rsi holds a physical pointer to real_mode_data.
 	 *
 	 * We come here either directly from a 64bit bootloader, or from
 	 * arch/x86/boot/compressed/head_64.S.
 	 *
 	 * We only come here initially at boot nothing else comes here.
 	 *
 	 * Since we may be loaded at an address different from what we were
 	 * compiled to run at we first fixup the physical addresses in our page
 	 * tables and then reload them.
 	 */

 	/* Set up the stack for verify_cpu() */
 	leaq	(__end_init_task - PTREGS_SIZE)(%rip), %rsp

 	leaq	_text(%rip), %rdi

 	/* Setup GSBASE to allow stack canary access for C code */
 	movl	$MSR_GS_BASE, %ecx
 	leaq	INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
 	movl	%edx, %eax
 	shrq	$32,  %rdx
 	wrmsr

 	pushq	%rsi
 	call	startup_64_setup_env
 	popq	%rsi

 #ifdef CONFIG_AMD_MEM_ENCRYPT
 	/*
 	 * Activate SEV/SME memory encryption if supported/enabled. This needs to
 	 * be done now, since this also includes setup of the SEV-SNP CPUID table,
 	 * which needs to be done before any CPUID instructions are executed in
 	 * subsequent code.
 	 */
 	movq	%rsi, %rdi
 	pushq	%rsi
 	call	sme_enable
 	popq	%rsi
 #endif

 	/* Now switch to __KERNEL_CS so IRET works reliably */
 	pushq	$__KERNEL_CS
 	leaq	.Lon_kernel_cs(%rip), %rax
 	pushq	%rax
 	lretq

 .Lon_kernel_cs:
 	UNWIND_HINT_EMPTY

 	/* Sanitize CPU configuration */
 	call verify_cpu

 	/*
 	 * Perform pagetable fixups. Additionally, if SME is active, encrypt
 	 * the kernel and retrieve the modifier (SME encryption mask if SME
 	 * is active) to be added to the initial pgdir entry that will be
 	 * programmed into CR3.
 	 */
 	leaq	_text(%rip), %rdi
 	pushq	%rsi
 	call	__startup_64
 	popq	%rsi

 	/* Form the CR3 value being sure to include the CR3 modifier */
 	addq	$(early_top_pgt - __START_KERNEL_map), %rax
 	jmp 1f
 SYM_CODE_END(startup_64)

 SYM_CODE_START(secondary_startup_64)
 	UNWIND_HINT_EMPTY
 	ANNOTATE_NOENDBR
 	/*
 	 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
 	 * and someone has loaded a mapped page table.
 	 *
 	 * %rsi holds a physical pointer to real_mode_data.
 	 *
 	 * We come here either from startup_64 (using physical addresses)
 	 * or from trampoline.S (using virtual addresses).
 	 *
 	 * Using virtual addresses from trampoline.S removes the need
 	 * to have any identity mapped pages in the kernel page table
 	 * after the boot processor executes this code.
 	 */

 	/* Sanitize CPU configuration */
 	call verify_cpu

 	/*
 	 * The secondary_startup_64_no_verify entry point is only used by
 	 * SEV-ES guests. In those guests the call to verify_cpu() would cause
 	 * #VC exceptions which can not be handled at this stage of secondary
 	 * CPU bringup.
 	 *
 	 * All non SEV-ES systems, especially Intel systems, need to execute
 	 * verify_cpu() above to make sure NX is enabled.
 	 */
 SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
 	UNWIND_HINT_EMPTY
 	ANNOTATE_NOENDBR

 	/*
 	 * Retrieve the modifier (SME encryption mask if SME is active) to be
 	 * added to the initial pgdir entry that will be programmed into CR3.
 	 */
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 	movq	sme_me_mask, %rax
 #else
 	xorq	%rax, %rax
 #endif

 	/* Form the CR3 value being sure to include the CR3 modifier */
 	addq	$(init_top_pgt - __START_KERNEL_map), %rax
 1:

 #ifdef CONFIG_X86_MCE
 	/*
 	 * Preserve CR4.MCE if the kernel will enable #MC support.
 	 * Clearing MCE may fault in some environments (that also force #MC
 	 * support). Any machine check that occurs before #MC support is fully
 	 * configured will crash the system regardless of the CR4.MCE value set
 	 * here.
 	 */
 	movq	%cr4, %rcx
 	andl	$X86_CR4_MCE, %ecx
 #else
 	movl	$0, %ecx
 #endif

 	/* Enable PAE mode, PGE and LA57 */
 	orl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
 #ifdef CONFIG_X86_5LEVEL
 	testl	$1, __pgtable_l5_enabled(%rip)
 	jz	1f
 	orl	$X86_CR4_LA57, %ecx
 1:
 #endif
 	movq	%rcx, %cr4

 	/* Setup early boot stage 4-/5-level pagetables. */
 	addq	phys_base(%rip), %rax

 	/*
 	 * For SEV guests: Verify that the C-bit is correct. A malicious
 	 * hypervisor could lie about the C-bit position to perform a ROP
 	 * attack on the guest by writing to the unencrypted stack and wait for
 	 * the next RET instruction.
 	 * %rsi carries pointer to realmode data and is callee-clobbered. Save
 	 * and restore it.
 	 */
 	pushq	%rsi
 	movq	%rax, %rdi
 	call	sev_verify_cbit
 	popq	%rsi

 	/*
 	 * Switch to new page-table
 	 *
 	 * For the boot CPU this switches to early_top_pgt which still has the
 	 * indentity mappings present. The secondary CPUs will switch to the
 	 * init_top_pgt here, away from the trampoline_pgd and unmap the
 	 * indentity mapped ranges.
 	 */
 	movq	%rax, %cr3

 	/*
 	 * Do a global TLB flush after the CR3 switch to make sure the TLB
 	 * entries from the identity mapping are flushed.
 	 */
 	movq	%cr4, %rcx
 	movq	%rcx, %rax
 	xorq	$X86_CR4_PGE, %rcx
 	movq	%rcx, %cr4
 	movq	%rax, %cr4

 	/* Ensure I am executing from virtual addresses */
 	movq	$1f, %rax
 	ANNOTATE_RETPOLINE_SAFE
 	jmp	*%rax
 1:
 	UNWIND_HINT_EMPTY
 	ANNOTATE_NOENDBR // above

 #ifdef CONFIG_SMP
 	movl	smpboot_control(%rip), %ecx

 	/* Get the per cpu offset for the given CPU# which is in ECX */
 	movq	__per_cpu_offset(,%rcx,8), %rdx
 #else
 	xorl	%edx, %edx /* zero-extended to clear all of RDX */
 #endif /* CONFIG_SMP */

 	/*
 	 * Setup a boot time stack - Any secondary CPU will have lost its stack
 	 * by now because the cr3-switch above unmaps the real-mode stack.
 	 *
 	 * RDX contains the per-cpu offset
 	 */
 	movq	pcpu_hot + X86_current_task(%rdx), %rax
 	movq	TASK_threadsp(%rax), %rsp

 	/*
 	 * We must switch to a new descriptor in kernel space for the GDT
 	 * because soon the kernel won't have access anymore to the userspace
 	 * addresses where we're currently running on. We have to do that here
 	 * because in 32bit we couldn't load a 64bit linear address.
 	 */
 	subq	$16, %rsp
 	movw	$(GDT_SIZE-1), (%rsp)
 	leaq	gdt_page(%rdx), %rax
 	movq	%rax, 2(%rsp)
 	lgdt	(%rsp)
 	addq	$16, %rsp

 	/* set up data segments */
 	xorl %eax,%eax
 	movl %eax,%ds
 	movl %eax,%ss
 	movl %eax,%es

 	/*
 	 * We don't really need to load %fs or %gs, but load them anyway
 	 * to kill any stale realmode selectors.  This allows execution
 	 * under VT hardware.
 	 */
 	movl %eax,%fs
 	movl %eax,%gs

 	/* Set up %gs.
 	 *
 	 * The base of %gs always points to fixed_percpu_data. If the
 	 * stack protector canary is enabled, it is located at %gs:40.
 	 * Note that, on SMP, the boot cpu uses init data section until
 	 * the per cpu areas are set up.
 	 */
 	movl	$MSR_GS_BASE,%ecx
 #ifndef CONFIG_SMP
 	leaq	INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
 #endif
 	movl	%edx, %eax
 	shrq	$32, %rdx
 	wrmsr

 	/* Setup and Load IDT */
 	pushq	%rsi
 	call	early_setup_idt
 	popq	%rsi

 	/* Check if nx is implemented */
 	movl	$0x80000001, %eax
 	cpuid
 	movl	%edx,%edi

 	/* Setup EFER (Extended Feature Enable Register) */
 	movl	$MSR_EFER, %ecx
 	rdmsr
 	/*
 	 * Preserve current value of EFER for comparison and to skip
 	 * EFER writes if no change was made (for TDX guest)
 	 */
 	movl    %eax, %edx
 	btsl	$_EFER_SCE, %eax	/* Enable System Call */
 	btl	$20,%edi		/* No Execute supported? */
 	jnc     1f
 	btsl	$_EFER_NX, %eax
 	btsq	$_PAGE_BIT_NX,early_pmd_flags(%rip)

 	/* Avoid writing EFER if no change was made (for TDX guest) */
 1:	cmpl	%edx, %eax
 	je	1f
 	xor	%edx, %edx
 	wrmsr				/* Make changes effective */
 1:
 	/* Setup cr0 */
 	movl	$CR0_STATE, %eax
 	/* Make changes effective */
 	movq	%rax, %cr0

 	/* zero EFLAGS after setting rsp */
 	pushq $0
 	popfq

 	/* rsi is pointer to real mode structure with interesting info.
 	   pass it to C */
 	movq	%rsi, %rdi

 .Ljump_to_C_code:
 	/*
 	 * Jump to run C code and to be on a real kernel address.
 	 * Since we are running on identity-mapped space we have to jump
 	 * to the full 64bit address, this is only possible as indirect
 	 * jump.  In addition we need to ensure %cs is set so we make this
 	 * a far return.
 	 *
 	 * Note: do not change to far jump indirect with 64bit offset.
 	 *
 	 * AMD does not support far jump indirect with 64bit offset.
 	 * AMD64 Architecture Programmer's Manual, Volume 3: states only
 	 *	JMP FAR mem16:16 FF /5 Far jump indirect,
 	 *		with the target specified by a far pointer in memory.
 	 *	JMP FAR mem16:32 FF /5 Far jump indirect,
 	 *		with the target specified by a far pointer in memory.
 	 *
 	 * Intel64 does support 64bit offset.
 	 * Software Developer Manual Vol 2: states:
 	 *	FF /5 JMP m16:16 Jump far, absolute indirect,
 	 *		address given in m16:16
 	 *	FF /5 JMP m16:32 Jump far, absolute indirect,
 	 *		address given in m16:32.
 	 *	REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
 	 *		address given in m16:64.
 	 */
 	pushq	$.Lafter_lret	# put return address on stack for unwinder
 	xorl	%ebp, %ebp	# clear frame pointer
 	movq	initial_code(%rip), %rax
 	pushq	$__KERNEL_CS	# set correct cs
 	pushq	%rax		# target address in negative space
 	lretq
 .Lafter_lret:
 	ANNOTATE_NOENDBR
 SYM_CODE_END(secondary_startup_64)

 #include "verify_cpu.S"
 #include "sev_verify_cbit.S"

 #ifdef CONFIG_HOTPLUG_CPU
 /*
  * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
  * up already except stack. We just set up stack here. Then call
  * start_secondary() via .Ljump_to_C_code.
  */
 SYM_CODE_START(start_cpu0)
 	ANNOTATE_NOENDBR
 	UNWIND_HINT_EMPTY

 	/* Find the idle task stack */
 	movq	PER_CPU_VAR(pcpu_hot) + X86_current_task, %rcx
 	movq	TASK_threadsp(%rcx), %rsp

 	jmp	.Ljump_to_C_code
 SYM_CODE_END(start_cpu0)
 #endif

 #ifdef CONFIG_AMD_MEM_ENCRYPT
 /*
  * VC Exception handler used during early boot when running on kernel
  * addresses, but before the switch to the idt_table can be made.
  * The early_idt_handler_array can't be used here because it calls into a lot
  * of __init code and this handler is also used during CPU offlining/onlining.
  * Therefore this handler ends up in the .text section so that it stays around
  * when .init.text is freed.
  */
 SYM_CODE_START_NOALIGN(vc_boot_ghcb)
 	UNWIND_HINT_IRET_REGS offset=8
 	ENDBR

 	ANNOTATE_UNRET_END

 	/* Build pt_regs */
 	PUSH_AND_CLEAR_REGS

 	/* Call C handler */
 	movq    %rsp, %rdi
 	movq	ORIG_RAX(%rsp), %rsi
 	movq	initial_vc_handler(%rip), %rax
 	ANNOTATE_RETPOLINE_SAFE
 	call	*%rax

 	/* Unwind pt_regs */
 	POP_REGS

 	/* Remove Error Code */
 	addq    $8, %rsp

 	iretq
 SYM_CODE_END(vc_boot_ghcb)
 #endif

 	/* Both SMP bootup and ACPI suspend change these variables */
 	__REFDATA
 	.balign	8
 SYM_DATA(initial_code,	.quad x86_64_start_kernel)
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 SYM_DATA(initial_vc_handler,	.quad handle_vc_boot_ghcb)
 #endif
 	__FINITDATA

 	__INIT
 SYM_CODE_START(early_idt_handler_array)
 	i = 0
 	.rept NUM_EXCEPTION_VECTORS
 	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
 		UNWIND_HINT_IRET_REGS
 		ENDBR
 		pushq $0	# Dummy error code, to make stack frame uniform
 	.else
 		UNWIND_HINT_IRET_REGS offset=8
 		ENDBR
 	.endif
 	pushq $i		# 72(%rsp) Vector number
 	jmp early_idt_handler_common
 	UNWIND_HINT_IRET_REGS
 	i = i + 1
 	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
 	.endr
 SYM_CODE_END(early_idt_handler_array)
 	ANNOTATE_NOENDBR // early_idt_handler_array[NUM_EXCEPTION_VECTORS]

 SYM_CODE_START_LOCAL(early_idt_handler_common)
 	UNWIND_HINT_IRET_REGS offset=16
 	ANNOTATE_UNRET_END
 	/*
 	 * The stack is the hardware frame, an error code or zero, and the
 	 * vector number.
 	 */
 	cld

 	incl early_recursion_flag(%rip)

 	/* The vector number is currently in the pt_regs->di slot. */
 	pushq %rsi				/* pt_regs->si */
 	movq 8(%rsp), %rsi			/* RSI = vector number */
 	movq %rdi, 8(%rsp)			/* pt_regs->di = RDI */
 	pushq %rdx				/* pt_regs->dx */
 	pushq %rcx				/* pt_regs->cx */
 	pushq %rax				/* pt_regs->ax */
 	pushq %r8				/* pt_regs->r8 */
 	pushq %r9				/* pt_regs->r9 */
 	pushq %r10				/* pt_regs->r10 */
 	pushq %r11				/* pt_regs->r11 */
 	pushq %rbx				/* pt_regs->bx */
 	pushq %rbp				/* pt_regs->bp */
 	pushq %r12				/* pt_regs->r12 */
 	pushq %r13				/* pt_regs->r13 */
 	pushq %r14				/* pt_regs->r14 */
 	pushq %r15				/* pt_regs->r15 */
 	UNWIND_HINT_REGS

 	movq %rsp,%rdi		/* RDI = pt_regs; RSI is already trapnr */
 	call do_early_exception

 	decl early_recursion_flag(%rip)
 	jmp restore_regs_and_return_to_kernel
 SYM_CODE_END(early_idt_handler_common)

 #ifdef CONFIG_AMD_MEM_ENCRYPT
 /*
  * VC Exception handler used during very early boot. The
  * early_idt_handler_array can't be used because it returns via the
  * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
  *
  * XXX it does, fix this.
  *
  * This handler will end up in the .init.text section and not be
  * available to boot secondary CPUs.
  */
 SYM_CODE_START_NOALIGN(vc_no_ghcb)
 	UNWIND_HINT_IRET_REGS offset=8
 	ENDBR

 	ANNOTATE_UNRET_END

 	/* Build pt_regs */
 	PUSH_AND_CLEAR_REGS

 	/* Call C handler */
 	movq    %rsp, %rdi
 	movq	ORIG_RAX(%rsp), %rsi
 	call    do_vc_no_ghcb

 	/* Unwind pt_regs */
 	POP_REGS

 	/* Remove Error Code */
 	addq    $8, %rsp

 	/* Pure iret required here - don't use INTERRUPT_RETURN */
 	iretq
 SYM_CODE_END(vc_no_ghcb)
 #endif

 #define SYM_DATA_START_PAGE_ALIGNED(name)			\
 	SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)

 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 /*
  * Each PGD needs to be 8k long and 8k aligned.  We do not
  * ever go out to userspace with these, so we do not
  * strictly *need* the second page, but this allows us to
  * have a single set_pgd() implementation that does not
  * need to worry about whether it has 4k or 8k to work
  * with.
  *
  * This ensures PGDs are 8k long:
  */
 #define PTI_USER_PGD_FILL	512
 /* This ensures they are 8k-aligned: */
 #define SYM_DATA_START_PTI_ALIGNED(name) \
 	SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
 #else
 #define SYM_DATA_START_PTI_ALIGNED(name) \
 	SYM_DATA_START_PAGE_ALIGNED(name)
 #define PTI_USER_PGD_FILL	0
 #endif

 /* Automate the creation of 1 to 1 mapping pmd entries */
 #define PMDS(START, PERM, COUNT)			\
 	i = 0 ;						\
 	.rept (COUNT) ;					\
 	.quad	(START) + (i << PMD_SHIFT) + (PERM) ;	\
 	i = i + 1 ;					\
 	.endr

 	__INITDATA
 	.balign 4

 SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
 	.fill	512,8,0
 	.fill	PTI_USER_PGD_FILL,8,0
 SYM_DATA_END(early_top_pgt)

 SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
 	.fill	512*EARLY_DYNAMIC_PAGE_TABLES,8,0
 SYM_DATA_END(early_dynamic_pgts)

 SYM_DATA(early_recursion_flag, .long 0)

 	.data

 #if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
 SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
 	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
 	.org    init_top_pgt + L4_PAGE_OFFSET*8, 0
 	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
 	.org    init_top_pgt + L4_START_KERNEL*8, 0
 	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
 	.quad   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
 	.fill	PTI_USER_PGD_FILL,8,0
 SYM_DATA_END(init_top_pgt)

 SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
 	.quad	level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
 	.fill	511, 8, 0
 SYM_DATA_END(level3_ident_pgt)
 SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
 	/*
 	 * Since I easily can, map the first 1G.
 	 * Don't set NX because code runs from these pages.
 	 *
 	 * Note: This sets _PAGE_GLOBAL despite whether
 	 * the CPU supports it or it is enabled.  But,
 	 * the CPU should ignore the bit.
 	 */
 	PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
 SYM_DATA_END(level2_ident_pgt)
 #else
 SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
 	.fill	512,8,0
 	.fill	PTI_USER_PGD_FILL,8,0
 SYM_DATA_END(init_top_pgt)
 #endif

 #ifdef CONFIG_X86_5LEVEL
 SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
 	.fill	511,8,0
 	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
 SYM_DATA_END(level4_kernel_pgt)
 #endif

 SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
 	.fill	L3_START_KERNEL,8,0
 	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
 	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
 	.quad	level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
 SYM_DATA_END(level3_kernel_pgt)

 SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
 	/*
 	 * Kernel high mapping.
 	 *
 	 * The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in
 	 * virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled,
 	 * 512 MiB otherwise.
 	 *
 	 * (NOTE: after that starts the module area, see MODULES_VADDR.)
 	 *
 	 * This table is eventually used by the kernel during normal runtime.
 	 * Care must be taken to clear out undesired bits later, like _PAGE_RW
 	 * or _PAGE_GLOBAL in some cases.
 	 */
 	PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE)
 SYM_DATA_END(level2_kernel_pgt)

 SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
 	.fill	(512 - 4 - FIXMAP_PMD_NUM),8,0
 	pgtno = 0
 	.rept (FIXMAP_PMD_NUM)
 	.quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
 		+ _PAGE_TABLE_NOENC;
 	pgtno = pgtno + 1
 	.endr
 	/* 6 MB reserved space + a 2MB hole */
 	.fill	4,8,0
 SYM_DATA_END(level2_fixmap_pgt)

 SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
 	.rept (FIXMAP_PMD_NUM)
 	.fill	512,8,0
 	.endr
 SYM_DATA_END(level1_fixmap_pgt)

 #undef PMDS

 	.data
 	.align 16

 SYM_DATA(smpboot_control,		.long 0)

 	.align 16
 /* This must match the first entry in level2_kernel_pgt */
 SYM_DATA(phys_base, .quad 0x0)
 EXPORT_SYMBOL(phys_base)

 #include "../../x86/xen/xen-head.S"

 	__PAGE_ALIGNED_BSS
 SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
 	.skip PAGE_SIZE
 SYM_DATA_END(empty_zero_page)
 EXPORT_SYMBOL(empty_zero_page)
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
	*
	* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
	* Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
	* Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
	* Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
	* Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
	*/


	#include <linux/linkage.h>
	#include <linux/threads.h>
	#include <linux/init.h>
	#include <linux/pgtable.h>
	#include <asm/segment.h>
	#include <asm/page.h>
	#include <asm/msr.h>
	#include <asm/cache.h>
	#include <asm/processor-flags.h>
	#include <asm/percpu.h>
	#include <asm/nops.h>
	#include "../entry/calling.h"
	#include <asm/export.h>
	#include <asm/nospec-branch.h>
	#include <asm/fixmap.h>

	/*
	* We are not able to switch in one step to the final KERNEL ADDRESS SPACE
	* because we need identity-mapped pages.
	*/
	#define l4_index(x) (((x) >> 39) & 511)
	#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

	L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
	L4_START_KERNEL = l4_index(__START_KERNEL_map)

	L3_START_KERNEL = pud_index(__START_KERNEL_map)

	.text
	__HEAD
	.code64
	SYM_CODE_START_NOALIGN(startup_64)
	UNWIND_HINT_EMPTY
	/*
	* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
	* and someone has loaded an identity mapped page table
	* for us. These identity mapped page tables map all of the
	* kernel pages and possibly all of memory.
	*
	* %rsi holds a physical pointer to real_mode_data.
	*
	* We come here either directly from a 64bit bootloader, or from
	* arch/x86/boot/compressed/head_64.S.
	*
	* We only come here initially at boot nothing else comes here.
	*
	* Since we may be loaded at an address different from what we were
	* compiled to run at we first fixup the physical addresses in our page
	* tables and then reload them.
	*/

	/* Set up the stack for verify_cpu() */
	leaq (__end_init_task - PTREGS_SIZE)(%rip), %rsp

	leaq _text(%rip), %rdi

	/* Setup GSBASE to allow stack canary access for C code */
	movl $MSR_GS_BASE, %ecx
	leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
	movl %edx, %eax
	shrq $32, %rdx
	wrmsr

	pushq %rsi
	call startup_64_setup_env
	popq %rsi

	#ifdef CONFIG_AMD_MEM_ENCRYPT
	/*
	* Activate SEV/SME memory encryption if supported/enabled. This needs to
	* be done now, since this also includes setup of the SEV-SNP CPUID table,
	* which needs to be done before any CPUID instructions are executed in
	* subsequent code.
	*/
	movq %rsi, %rdi
	pushq %rsi
	call sme_enable
	popq %rsi
	#endif

	/* Now switch to __KERNEL_CS so IRET works reliably */
	pushq $__KERNEL_CS
	leaq .Lon_kernel_cs(%rip), %rax
	pushq %rax
	lretq

	.Lon_kernel_cs:
	UNWIND_HINT_EMPTY

	/* Sanitize CPU configuration */
	call verify_cpu

	/*
	* Perform pagetable fixups. Additionally, if SME is active, encrypt
	* the kernel and retrieve the modifier (SME encryption mask if SME
	* is active) to be added to the initial pgdir entry that will be
	* programmed into CR3.
	*/
	leaq _text(%rip), %rdi
	pushq %rsi
	call __startup_64
	popq %rsi

	/* Form the CR3 value being sure to include the CR3 modifier */
	addq $(early_top_pgt - __START_KERNEL_map), %rax
	jmp 1f
	SYM_CODE_END(startup_64)

	SYM_CODE_START(secondary_startup_64)
	UNWIND_HINT_EMPTY
	ANNOTATE_NOENDBR
	/*
	* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
	* and someone has loaded a mapped page table.
	*
	* %rsi holds a physical pointer to real_mode_data.
	*
	* We come here either from startup_64 (using physical addresses)
	* or from trampoline.S (using virtual addresses).
	*
	* Using virtual addresses from trampoline.S removes the need
	* to have any identity mapped pages in the kernel page table
	* after the boot processor executes this code.
	*/

	/* Sanitize CPU configuration */
	call verify_cpu

	/*
	* The secondary_startup_64_no_verify entry point is only used by
	* SEV-ES guests. In those guests the call to verify_cpu() would cause
	* #VC exceptions which can not be handled at this stage of secondary
	* CPU bringup.
	*
	* All non SEV-ES systems, especially Intel systems, need to execute
	* verify_cpu() above to make sure NX is enabled.
	*/
	SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
	UNWIND_HINT_EMPTY
	ANNOTATE_NOENDBR

	/*
	* Retrieve the modifier (SME encryption mask if SME is active) to be
	* added to the initial pgdir entry that will be programmed into CR3.
	*/
	#ifdef CONFIG_AMD_MEM_ENCRYPT
	movq sme_me_mask, %rax
	#else
	xorq %rax, %rax
	#endif

	/* Form the CR3 value being sure to include the CR3 modifier */
	addq $(init_top_pgt - __START_KERNEL_map), %rax
	1:

	#ifdef CONFIG_X86_MCE
	/*
	* Preserve CR4.MCE if the kernel will enable #MC support.
	* Clearing MCE may fault in some environments (that also force #MC
	* support). Any machine check that occurs before #MC support is fully
	* configured will crash the system regardless of the CR4.MCE value set
	* here.
	*/
	movq %cr4, %rcx
	andl $X86_CR4_MCE, %ecx
	#else
	movl $0, %ecx
	#endif

	/* Enable PAE mode, PGE and LA57 */
	orl $(X86_CR4_PAE \| X86_CR4_PGE), %ecx
	#ifdef CONFIG_X86_5LEVEL
	testl $1, __pgtable_l5_enabled(%rip)
	jz 1f
	orl $X86_CR4_LA57, %ecx
	1:
	#endif
	movq %rcx, %cr4

	/* Setup early boot stage 4-/5-level pagetables. */
	addq phys_base(%rip), %rax

	/*
	* For SEV guests: Verify that the C-bit is correct. A malicious
	* hypervisor could lie about the C-bit position to perform a ROP
	* attack on the guest by writing to the unencrypted stack and wait for
	* the next RET instruction.
	* %rsi carries pointer to realmode data and is callee-clobbered. Save
	* and restore it.
	*/
	pushq %rsi
	movq %rax, %rdi
	call sev_verify_cbit
	popq %rsi

	/*
	* Switch to new page-table
	*
	* For the boot CPU this switches to early_top_pgt which still has the
	* indentity mappings present. The secondary CPUs will switch to the
	* init_top_pgt here, away from the trampoline_pgd and unmap the
	* indentity mapped ranges.
	*/
	movq %rax, %cr3

	/*
	* Do a global TLB flush after the CR3 switch to make sure the TLB
	* entries from the identity mapping are flushed.
	*/
	movq %cr4, %rcx
	movq %rcx, %rax
	xorq $X86_CR4_PGE, %rcx
	movq %rcx, %cr4
	movq %rax, %cr4

	/* Ensure I am executing from virtual addresses */
	movq $1f, %rax
	ANNOTATE_RETPOLINE_SAFE
	jmp *%rax
	1:
	UNWIND_HINT_EMPTY
	ANNOTATE_NOENDBR // above

	#ifdef CONFIG_SMP
	movl smpboot_control(%rip), %ecx

	/* Get the per cpu offset for the given CPU# which is in ECX */
	movq __per_cpu_offset(,%rcx,8), %rdx
	#else
	xorl %edx, %edx /* zero-extended to clear all of RDX */
	#endif /* CONFIG_SMP */

	/*
	* Setup a boot time stack - Any secondary CPU will have lost its stack
	* by now because the cr3-switch above unmaps the real-mode stack.
	*
	* RDX contains the per-cpu offset
	*/
	movq pcpu_hot + X86_current_task(%rdx), %rax
	movq TASK_threadsp(%rax), %rsp

	/*
	* We must switch to a new descriptor in kernel space for the GDT
	* because soon the kernel won't have access anymore to the userspace
	* addresses where we're currently running on. We have to do that here
	* because in 32bit we couldn't load a 64bit linear address.
	*/
	subq $16, %rsp
	movw $(GDT_SIZE-1), (%rsp)
	leaq gdt_page(%rdx), %rax
	movq %rax, 2(%rsp)
	lgdt (%rsp)
	addq $16, %rsp

	/* set up data segments */
	xorl %eax,%eax
	movl %eax,%ds
	movl %eax,%ss
	movl %eax,%es

	/*
	* We don't really need to load %fs or %gs, but load them anyway
	* to kill any stale realmode selectors. This allows execution
	* under VT hardware.
	*/
	movl %eax,%fs
	movl %eax,%gs

	/* Set up %gs.
	*
	* The base of %gs always points to fixed_percpu_data. If the
	* stack protector canary is enabled, it is located at %gs:40.
	* Note that, on SMP, the boot cpu uses init data section until
	* the per cpu areas are set up.
	*/
	movl $MSR_GS_BASE,%ecx
	#ifndef CONFIG_SMP
	leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
	#endif
	movl %edx, %eax
	shrq $32, %rdx
	wrmsr

	/* Setup and Load IDT */
	pushq %rsi
	call early_setup_idt
	popq %rsi

	/* Check if nx is implemented */
	movl $0x80000001, %eax
	cpuid
	movl %edx,%edi

	/* Setup EFER (Extended Feature Enable Register) */
	movl $MSR_EFER, %ecx
	rdmsr
	/*
	* Preserve current value of EFER for comparison and to skip
	* EFER writes if no change was made (for TDX guest)
	*/
	movl %eax, %edx
	btsl $_EFER_SCE, %eax /* Enable System Call */
	btl $20,%edi /* No Execute supported? */
	jnc 1f
	btsl $_EFER_NX, %eax
	btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)

	/* Avoid writing EFER if no change was made (for TDX guest) */
	1: cmpl %edx, %eax
	je 1f
	xor %edx, %edx
	wrmsr /* Make changes effective */
	1:
	/* Setup cr0 */
	movl $CR0_STATE, %eax
	/* Make changes effective */
	movq %rax, %cr0

	/* zero EFLAGS after setting rsp */
	pushq $0
	popfq

	/* rsi is pointer to real mode structure with interesting info.
	pass it to C */
	movq %rsi, %rdi

	.Ljump_to_C_code:
	/*
	* Jump to run C code and to be on a real kernel address.
	* Since we are running on identity-mapped space we have to jump
	* to the full 64bit address, this is only possible as indirect
	* jump. In addition we need to ensure %cs is set so we make this
	* a far return.
	*
	* Note: do not change to far jump indirect with 64bit offset.
	*
	* AMD does not support far jump indirect with 64bit offset.
	* AMD64 Architecture Programmer's Manual, Volume 3: states only
	* JMP FAR mem16:16 FF /5 Far jump indirect,
	* with the target specified by a far pointer in memory.
	* JMP FAR mem16:32 FF /5 Far jump indirect,
	* with the target specified by a far pointer in memory.
	*
	* Intel64 does support 64bit offset.
	* Software Developer Manual Vol 2: states:
	* FF /5 JMP m16:16 Jump far, absolute indirect,
	* address given in m16:16
	* FF /5 JMP m16:32 Jump far, absolute indirect,
	* address given in m16:32.
	* REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
	* address given in m16:64.
	*/
	pushq $.Lafter_lret # put return address on stack for unwinder
	xorl %ebp, %ebp # clear frame pointer
	movq initial_code(%rip), %rax
	pushq $__KERNEL_CS # set correct cs
	pushq %rax # target address in negative space
	lretq
	.Lafter_lret:
	ANNOTATE_NOENDBR
	SYM_CODE_END(secondary_startup_64)

	#include "verify_cpu.S"
	#include "sev_verify_cbit.S"

	#ifdef CONFIG_HOTPLUG_CPU
	/*
	* Boot CPU0 entry point. It's called from play_dead(). Everything has been set
	* up already except stack. We just set up stack here. Then call
	* start_secondary() via .Ljump_to_C_code.
	*/
	SYM_CODE_START(start_cpu0)
	ANNOTATE_NOENDBR
	UNWIND_HINT_EMPTY

	/* Find the idle task stack */
	movq PER_CPU_VAR(pcpu_hot) + X86_current_task, %rcx
	movq TASK_threadsp(%rcx), %rsp

	jmp .Ljump_to_C_code
	SYM_CODE_END(start_cpu0)
	#endif

	#ifdef CONFIG_AMD_MEM_ENCRYPT
	/*
	* VC Exception handler used during early boot when running on kernel
	* addresses, but before the switch to the idt_table can be made.
	* The early_idt_handler_array can't be used here because it calls into a lot
	* of __init code and this handler is also used during CPU offlining/onlining.
	* Therefore this handler ends up in the .text section so that it stays around
	* when .init.text is freed.
	*/
	SYM_CODE_START_NOALIGN(vc_boot_ghcb)
	UNWIND_HINT_IRET_REGS offset=8
	ENDBR

	ANNOTATE_UNRET_END

	/* Build pt_regs */
	PUSH_AND_CLEAR_REGS

	/* Call C handler */
	movq %rsp, %rdi
	movq ORIG_RAX(%rsp), %rsi
	movq initial_vc_handler(%rip), %rax
	ANNOTATE_RETPOLINE_SAFE
	call *%rax

	/* Unwind pt_regs */
	POP_REGS

	/* Remove Error Code */
	addq $8, %rsp

	iretq
	SYM_CODE_END(vc_boot_ghcb)
	#endif

	/* Both SMP bootup and ACPI suspend change these variables */
	__REFDATA
	.balign 8
	SYM_DATA(initial_code, .quad x86_64_start_kernel)
	#ifdef CONFIG_AMD_MEM_ENCRYPT
	SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb)
	#endif
	__FINITDATA

	__INIT
	SYM_CODE_START(early_idt_handler_array)
	i = 0
	.rept NUM_EXCEPTION_VECTORS
	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
	UNWIND_HINT_IRET_REGS
	ENDBR
	pushq $0 # Dummy error code, to make stack frame uniform
	.else
	UNWIND_HINT_IRET_REGS offset=8
	ENDBR
	.endif
	pushq $i # 72(%rsp) Vector number
	jmp early_idt_handler_common
	UNWIND_HINT_IRET_REGS
	i = i + 1
	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
	.endr
	SYM_CODE_END(early_idt_handler_array)
	ANNOTATE_NOENDBR // early_idt_handler_array[NUM_EXCEPTION_VECTORS]

	SYM_CODE_START_LOCAL(early_idt_handler_common)
	UNWIND_HINT_IRET_REGS offset=16
	ANNOTATE_UNRET_END
	/*
	* The stack is the hardware frame, an error code or zero, and the
	* vector number.
	*/
	cld

	incl early_recursion_flag(%rip)

	/* The vector number is currently in the pt_regs->di slot. */
	pushq %rsi /* pt_regs->si */
	movq 8(%rsp), %rsi /* RSI = vector number */
	movq %rdi, 8(%rsp) /* pt_regs->di = RDI */
	pushq %rdx /* pt_regs->dx */
	pushq %rcx /* pt_regs->cx */
	pushq %rax /* pt_regs->ax */
	pushq %r8 /* pt_regs->r8 */
	pushq %r9 /* pt_regs->r9 */
	pushq %r10 /* pt_regs->r10 */
	pushq %r11 /* pt_regs->r11 */
	pushq %rbx /* pt_regs->bx */
	pushq %rbp /* pt_regs->bp */
	pushq %r12 /* pt_regs->r12 */
	pushq %r13 /* pt_regs->r13 */
	pushq %r14 /* pt_regs->r14 */
	pushq %r15 /* pt_regs->r15 */
	UNWIND_HINT_REGS

	movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */
	call do_early_exception

	decl early_recursion_flag(%rip)
	jmp restore_regs_and_return_to_kernel
	SYM_CODE_END(early_idt_handler_common)

	#ifdef CONFIG_AMD_MEM_ENCRYPT
	/*
	* VC Exception handler used during very early boot. The
	* early_idt_handler_array can't be used because it returns via the
	* paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
	*
	* XXX it does, fix this.
	*
	* This handler will end up in the .init.text section and not be
	* available to boot secondary CPUs.
	*/
	SYM_CODE_START_NOALIGN(vc_no_ghcb)
	UNWIND_HINT_IRET_REGS offset=8
	ENDBR

	ANNOTATE_UNRET_END

	/* Build pt_regs */
	PUSH_AND_CLEAR_REGS

	/* Call C handler */
	movq %rsp, %rdi
	movq ORIG_RAX(%rsp), %rsi
	call do_vc_no_ghcb

	/* Unwind pt_regs */
	POP_REGS

	/* Remove Error Code */
	addq $8, %rsp

	/* Pure iret required here - don't use INTERRUPT_RETURN */
	iretq
	SYM_CODE_END(vc_no_ghcb)
	#endif

	#define SYM_DATA_START_PAGE_ALIGNED(name) \
	SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)

	#ifdef CONFIG_PAGE_TABLE_ISOLATION
	/*
	* Each PGD needs to be 8k long and 8k aligned. We do not
	* ever go out to userspace with these, so we do not
	* strictly need the second page, but this allows us to
	* have a single set_pgd() implementation that does not
	* need to worry about whether it has 4k or 8k to work
	* with.
	*
	* This ensures PGDs are 8k long:
	*/
	#define PTI_USER_PGD_FILL 512
	/* This ensures they are 8k-aligned: */
	#define SYM_DATA_START_PTI_ALIGNED(name) \
	SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
	#else
	#define SYM_DATA_START_PTI_ALIGNED(name) \
	SYM_DATA_START_PAGE_ALIGNED(name)
	#define PTI_USER_PGD_FILL 0
	#endif

	/* Automate the creation of 1 to 1 mapping pmd entries */
	#define PMDS(START, PERM, COUNT) \
	i = 0 ; \
	.rept (COUNT) ; \
	.quad (START) + (i << PMD_SHIFT) + (PERM) ; \
	i = i + 1 ; \
	.endr

	__INITDATA
	.balign 4

	SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
	.fill 512,8,0
	.fill PTI_USER_PGD_FILL,8,0
	SYM_DATA_END(early_top_pgt)

	SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
	.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
	SYM_DATA_END(early_dynamic_pgts)

	SYM_DATA(early_recursion_flag, .long 0)

	.data

	#if defined(CONFIG_XEN_PV) \|\| defined(CONFIG_PVH)
	SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
	.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.org init_top_pgt + L4_PAGE_OFFSET*8, 0
	.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.org init_top_pgt + L4_START_KERNEL*8, 0
	/* (2^48-(2102410241024))/(2^39) = 511 /
	.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
	.fill PTI_USER_PGD_FILL,8,0
	SYM_DATA_END(init_top_pgt)

	SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
	.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.fill 511, 8, 0
	SYM_DATA_END(level3_ident_pgt)
	SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
	/*
	* Since I easily can, map the first 1G.
	* Don't set NX because code runs from these pages.
	*
	* Note: This sets _PAGE_GLOBAL despite whether
	* the CPU supports it or it is enabled. But,
	* the CPU should ignore the bit.
	*/
	PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
	SYM_DATA_END(level2_ident_pgt)
	#else
	SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
	.fill 512,8,0
	.fill PTI_USER_PGD_FILL,8,0
	SYM_DATA_END(init_top_pgt)
	#endif

	#ifdef CONFIG_X86_5LEVEL
	SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
	.fill 511,8,0
	.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
	SYM_DATA_END(level4_kernel_pgt)
	#endif

	SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
	.fill L3_START_KERNEL,8,0
	/* (2^48-(2102410241024)-((2^39)511))/(2^30) = 510 */
	.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
	SYM_DATA_END(level3_kernel_pgt)

	SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
	/*
	* Kernel high mapping.
	*
	* The kernel code+data+bss must be located below KERNEL_IMAGE_SIZE in
	* virtual address space, which is 1 GiB if RANDOMIZE_BASE is enabled,
	* 512 MiB otherwise.
	*
	* (NOTE: after that starts the module area, see MODULES_VADDR.)
	*
	* This table is eventually used by the kernel during normal runtime.
	* Care must be taken to clear out undesired bits later, like _PAGE_RW
	* or _PAGE_GLOBAL in some cases.
	*/
	PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE)
	SYM_DATA_END(level2_kernel_pgt)

	SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
	.fill (512 - 4 - FIXMAP_PMD_NUM),8,0
	pgtno = 0
	.rept (FIXMAP_PMD_NUM)
	.quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
	+ _PAGE_TABLE_NOENC;
	pgtno = pgtno + 1
	.endr
	/* 6 MB reserved space + a 2MB hole */
	.fill 4,8,0
	SYM_DATA_END(level2_fixmap_pgt)

	SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
	.rept (FIXMAP_PMD_NUM)
	.fill 512,8,0
	.endr
	SYM_DATA_END(level1_fixmap_pgt)

	#undef PMDS

	.data
	.align 16

	SYM_DATA(smpboot_control, .long 0)

	.align 16
	/* This must match the first entry in level2_kernel_pgt */
	SYM_DATA(phys_base, .quad 0x0)
	EXPORT_SYMBOL(phys_base)

	#include "../../x86/xen/xen-head.S"

	__PAGE_ALIGNED_BSS
	SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
	.skip PAGE_SIZE
	SYM_DATA_END(empty_zero_page)
	EXPORT_SYMBOL(empty_zero_page)